Product quality is related to the survival and development of each enterprise. Product quality is determined by the five major production factors in the production process: people (Man), equipment (Machine), materials (Material), methods (Method), environment (Environment), This is what we often call the 4MIE rule. Since domestic plastic color printing manufacturers vary greatly in size and grade, the importance and actual implementation of the 4MIE law are also different. Due to the limitation of capital strength, for most small and medium-sized plastic color printing factories, it is highly operable to keep the printing raw materials well and reduce quality accidents from the source. In the process of plastic color printing, the raw materials are mainly film, ink and solvent. The overall quality control principle: determine the appropriate film and structure according to the customer's specific requirements or the characteristics of the package content and post-processing; after selecting the material structure, determine the appropriate ink according to different films, and matching the corresponding Solvent; avoid excessive packaging or sub-filling.
There are many types of films on the market, but the most commonly used printing films are BOPP, NY, PET, PE. As far as printing is concerned, the most important thing is of course the surface treatment effect of the film and whether the NY film is damp. When printing, the process requirements for measuring the surface tension of the film by one film roll and one measurement should be formulated. The corona effect is time-sensitive. If it is left for a long time, the corona effect may drop too much to meet the requirements of printing; it can also avoid the hidden trouble of accidentally reversing the printing on the film surface. PE film is the main object we should pay attention to: there may be a corona treatment when the film roll is blown; the corona effect is not enough due to the excessive thickness or unevenness of the film; the film is added too much slip agent or refreshing Excessive proportion of slip material causes the corona effect to decrease greatly. When the corona effect on both sides of the 12 ~ 15umPET film is not much different, it is easy to cause the back sticking failure of the printed film roll. Corona requirements for printed films: BOPP, PE ≥38 dynes, PET ≥50 dynes, NY ≥52 dynes. After the NY film absorbs water, it will not have a great impact on the corona effect. Determine whether the NY film absorbs water to see if the film shrinks. If you cut a film and put it in the oven for a few hours, if the feel is hard, if there is a trend , Hard, etc., the NY film absorbs too much water. When purchasing a film, you must explain to the supplier the purpose and requirements of the film. Now the film varieties are refined. If you say the names of PET, NY, BOPP, the supplier may have several varieties, but they are not necessarily suitable.
When choosing gravure inks, we must first consider a few factors: on what substrate to print? What kind of machine is used for printing? What kind of effect do you want? What are the post-print processing and end-product use conditions? Ink manufacturers are now fiercely competitive and have a large selection of products, which may also dazzle our color printing plants. Before printing, confirm the above points. Both choose the ink with the best performance and price ratio, and can reduce or avoid the occurrence of printing failures. . Ink suppliers should not be too many, not more than three. Ink of different brands cannot be blended and used, which causes a lot of waste of remaining ink; maybe some color printing manufacturers hold the mentality of occupying ink supplier funds, but the business should be Sincerity-based, it is necessary to pay sooner or later, there is no need for this.
There are three common types of ink on the market: polyamide type surface printing ink, chlorinated polypropylene type compound ink, and polyurethane ink. Choose different matching inks for different substrates. For printing BOPP, chlorinated polypropylene compound ink is used. If compounding is not needed, polyamide-type surface printing ink is used. If general-purpose polyurethane ink is used for printing BOPP, not only the cost is high, but also the adhesion fastness cannot meet the requirements. NY, PET film must be printed with polyurethane ink. If it is printed with chlorinated polypropylene ink, it is prone to failures such as low peel strength and high temperature delamination. The adhesion of polyamide type ink to PE film is particularly good, but it can only be used for general dry packaging. When making high temperature, grease and water resistant packaging, such as milk film and bottle label, polyurethane ink should be preferred.
There are several basic indicators of ink that our color printing companies should test: viscosity, fineness, hue, and fastness to adhesion. The necessary test tools include scraper (contrast hue, measurement of adhesion fastness), 3 # Cha Enhuai (viscosity), fineness plate (fineness). When testing viscosity, it is best to dilute it to a specific viscosity (for example, 18 seconds / 25 ° C) with the supporting mixed solvent, and calculate the amount of solvent added, so as to eliminate the "false viscosity" phenomenon that some inks may bring (ink see It's very thick, but it doesn't add solvent). The test of adhesion fastness can use the national standard (GB / T 13217.7-91), but it may not be enough for some surface printing inks. It is best to simulate the specific requirements of product packaging and post-processing conditions for testing.
The good ring of solvent quality directly affects the quality of ink printing, but for general SMEs, the solvent quality is the most difficult to grasp. The main indicators to distinguish between good and bad solvents are purity and moisture content. The quantitative and qualitative detection of solvents is best detected by chromatography, but the required instruments are more expensive and the technical requirements are higher. If it is just for printing, and does not consider the dry composite process, here are a few simple and practical methods. Judging from the appearance of the solvent, at least it should be clear and transparent. If there is turbidity or floating matter, the solvent should be used with caution. Smell the smell of the solvent, after a long time of contact with the commonly used solvents, the operator has a general impression of the smell of a particular solvent. If the smell of the batch of solvents is found to be impure, it can be sure that the batch of solvents is not high in purity and the impurities many. Use the principle of different dissolving effects to roughly determine the water content of the solvent: use a 100ml glass graduated cylinder to take a large half of the transparent toluene solvent, take a small amount of the ester or ketone solvent to be measured, and evenly pour into toluene. When adding toluene, observe whether there is turbidity (milky white) phenomenon. If there is, the water content in the solvent seriously exceeds the standard. Experience shows that this phenomenon is obvious when the water content exceeds 0.5%. The moisture test of benzene solvents can be determined by drawing the solvent through a long glass tube and observing whether there is delamination.
There are many factors that affect the quality of printing. How to better grasp the quality of printed matter, each color printing company has its own management method. The quality control of raw materials is the most basic and critical process requirement in the color printing process. It is difficult to imagine that unqualified or inappropriate raw materials can guarantee the production of quality printed products. Therefore, our color printing enterprises must be durable and effective The quality of raw materials is critical.
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